Method for oxygenating wastewater

ABSTRACT

A method and apparatus creates gas-enriched fluid that is used to treat wastewater. In one embodiment, the wastewater is withdrawn from a supply of wastewater to be treated, and the wastewater is delivered in an atomized manner to a vessel pressurized with gas to form gas-enriched wastewater. The gas-enriched wastewater is then delivered to the supply of wastewater to be treated.

CROSS-REFERENCE TO THE RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.09/632,530, filed Aug. 4, 2000.

FIELD OF THE INVENTION

The present invention relates generally to a system and method forgas-enriching water and, more particularly, to a system and method forproviding large volumes of oxygen-enriched water to a reservoir, tank,pond, stream, etc. to help meet its biochemical oxygen demand.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofart which may be related to various aspects of the present inventionwhich are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Any natural waterway has the ability to assimilate organic matter. Whenthe loading of organic matter exceeds this assimilative capacity, thewater resource is impaired for this reason. Waste, whether human orindustrial, is treated for safe release into the environment. Forexample, wastewater from municipalities and industry is treated beforedischarge into waterways such as rivers. In many cases, these treatmentsaccelerate the natural assimilation process by introducing additionaloxygen to the biological process of degrading the waste.

Pollution, or contamination, of water is a serious problem throughoutthe world, particularly in the United States. Various sources ofcontamination are responsible for water pollution, including industrialand municipal entities. Industrial entities may discharge liquid ortwo-phase (liquid/solid) waste indirectly or directly into theenvironment, such as into rivers and lakes, contaminating the watersupply and harming the environment, fish and wildlife. Air pollution isalso a problem, particularly industrial air pollution, because airbornecontaminants may be collected by rainfall and runoff into bodies ofwater. Industrial waste may include heavy metals, hydrocarbons,generally toxic materials, and many other known and unknowncontaminants. In addition, wastewater and air pollution typically emitan undesirable odor from the contaminants, which may be a result ofinsufficient wastewater treatment or inefficient industrial systems(e.g., inefficient combustion, chemical reactions or processes, etc.)creating such contaminants.

Municipalities also produce considerable waste. Particularly, combinedsewer overflows (CSOs), sanitary sewer overflows (SSOs), and stormwaterdischarges can create significant problems. Sewage carries bacteria,viruses, protozoa (parasitic organisms), helminths (intestinal worms),and bioaerosols (inhalable molds and fungi) among many othercontaminants. Combined sewers are remnants of early sewage systems,which use a common pipe to collect both storm water runoff and sanitarysewage. During periods of rainfall or snowmelt, these combined sewersare designed to overflow directly into nearby streams, rivers, lakes orestuaries. SSOs are discharges of sewage from a separate sanitary sewercollection system, which may overflow prior to reaching a sewagetreatment plant. Sanitary sewers may overflow for a variety of reasons,such as inadequate or deteriorating systems, broken or leaky pipes,and/or excessive rain or snowfall infiltrating leaky pipes through theground. Finally, storm water runoff adds to the problem, as pollutantsare collected en route to rivers, streams, lakes, or into combined andsanitary sewers. Storm water picks up contaminants from fertilizers,pesticides, oil and grease from automobiles, exhaust residue, airpollution fallout, bacteria from animals, decayed vegetation, and manyother known and unknown contaminants.

Water contamination may be site specific, as with many industrialentities, or it may be non-site specific as with many CSOs, SSOs, andstorm water runoffs. Although the discussion has been limited toindustrial and municipal waste, contamination may arise from a varietyof sources and accumulate in various site specific and non-site specificlocations. For example, agricultural waste, pesticides and fertilizerscreate site specific water contamination, such as in ponds, streams,irrigation, ground water and drinking water for the animals and people.

Today, the most common waste treatment method is aerobic biologicaldegradation, which uses microorganisms, commonly referred to as “bugs,”to biodegrade waste. In a wastewater treatment application, aerobicbiological degradation typically involves an aeration/activated sludgeprocess in which oxygen is added to one or more tanks containing thewastewater to be treated. The oxygen supports the microorganisms whilethey degrade the compounds in the wastewater. To enable themicroorganisms to grow and degrade the waste and, ultimately, to reducethe biochemical oxygen demand (BOD), i.e., the amount of oxygen requiredby microorganisms during stabilization of decomposable organic matterunder aerobic conditions, in the treatment system, sufficient oxygenmust be available. In some systems, additional oxygen is required toalso reduce nitrogen levels in the effluent.

Typically, waste treatment plants use mechanical or diffuse aerators tosupport the growth of microorganisms. Mechanical aerators typicallyemploy a blade or propeller placed just beneath the surface of a pond,tank, or other reservoir to induce air into the wastewater by mixing.Such mixers generally have relatively low initial capital costs, butoften require substantial amounts of energy to operate.

Alternatively, diffused aerators introduce air or oxygen into wastewaterby blowing gas bubbles into the reservoir, typically near its bottom.Diffused aerators, depending upon design, may produce either coarse orfine bubbles. Coarse bubbles are produced through a diffuser with largerholes and typically range in size from 4 to 6 mm in diameter or larger.Fine bubbles, on the other hand, are produced through a diffusers withsmaller holes and typically range in size from 0.5 to 2 mm in diameter.Diffused aerators typically have lower initial costs, as well as loweroperating and maintenance costs, than mechanical aerators.

Mechanical and diffused aerators involve driving off volatile organiccompounds (VOC's) and contributing to odor issues while transferringoxygen in a gaseous state into liquid wastewater, with oxygen transferoccurring mainly as a result of diffusion across the gas-liquidboundary. For example, in the case of diffused aerators using pureoxygen, the gas-liquid boundary is defined by the outer surfaces of theair bubbles introduced into the treatment site. Generally, fine bubbleaerators are more efficient than coarse bubble and mechanical aeratorsdue to the increased total surface area available for oxygen transferthat is associated with the fine bubbles. The performance of fine bubbleaeration degrades over time if regular maintenance is not used.

However, more efficient apparatus and methods for oxygenating wastewaterstill are needed. Municipal wastewater needs typically grow as themunicipality grows in population. To meet increasing needs,municipalities either expand existing wastewater treatment facilities orbuild additional wastewater treatment facilities. Either option requiresadditional land and new equipment. Thus, much expense may be saved byenhancing the operating efficiency of existing facilities in response toincreased demand for wastewater treatment.

A municipal wastewater treatment process, for example, typicallyinvolves a primary treatment process, which generally includes aninitial screening and clarification, followed by a biological treatmentprocess, sometimes referred to as a secondary treatment process. Thewastewater entering the activated sludge process may have about sixtypercent of suspended solids, thirty percent of BOD, and about fiftypercent of pathogens removed in the primary treatment (although in someprocesses primary clarification may be omitted so that the solidsotherwise removed are available for food for the microorganisms workingin the secondary process).

The activated sludge process typically consists of one or more aerationtanks or basins in which oxygen is added to fuel the microorganismsdegrading the organic compounds. After leaving the aeration tank(s) thewater enters a secondary clarifier in which the activatedsludge/microorganisms settle out. After passing through this activatedsludge process the water typically has about 90% of the suspended solidsand 80-90% of the BOD removed. The water is ready for either moreadvanced secondary or tertiary treatments, or for return to a naturalwaterway. The choice typically depends upon the effluent levels andlocal regulations.

Alternately, wastewater treatment may occur in a sequencing batchreactor (SBR). SBR treatment generally is the same as an activatedsludge system, except that the process is performed in only one tank,whereas activated sludge systems may use several tanks. SBRs may be usedas an alternative to an activated sludge process, in regular secondarytreatment, or for more advanced treatment processes, e.g.,nitrification/denitrification and phosphorus removal. SBRs may processnumerous batches per day. Typically, for industrial applications SBRsprocess one to three batches per day, whereas for municipal applicationsSBRs may process four to eight batches per day.

The operation of an SBR generally includes five separate phases: fill,react, settle, decant, and idle, although there may be alternatives tothese SBR phases depending upon the circumstances involved in aparticular application. In the fill phase, wastewater enters the reactortank through a port near the bottom of the basin, after which the inletvalve is closed. Aeration and mixing may begin during the fill. In thereact phase, the inlet is closed and aeration and mixing continues orbegins. In the settle phase, the remaining solids settle to the bottomof the basin. In the decant phase, fluid is removed from the surface ofthe basin by a decanter. During this time settled sludge also may beremoved. In the idle phase, the reactor awaits a new batch ofwastewater, typically with a portion of the biomass remaining in thebasin to provide food for the microorganisms in the next batch.

The owners and operators of wastewater treatment plants often search forways to lower the cost of remaining in compliance with local, state,and/or federal laws regulating such plants. One way of lower operatingcosts has been to pursue energy conservation measures to achieve loweroperating and maintenance costs. One particular target has been thesubstantial electricity and other energy costs associated with theoperation of conventional systems for aerating wastewater. Aeration canaccount for more than half of municipal wastewater treatment energyconsumption. However, despite past focus on improving oxygen deliverysystems to deliver higher levels of oxygen into wastewater moreefficiently, there remains a need for further improvement, i.e., anapparatus and method for delivering large quantities of oxygen inconjunction with wastewater treatment applications. Furthermore, aflexible waste treatment apparatus and method is needed to adequatelyaddress non-site specific water pollution, for example, in stream waterpollution resulting from CSOs, SSOs and storm water runoff, and specialand/or smaller applications such wastewater and odor control on farms.

SUMMARY OF THE INVENTION

The present invention may address one or more of the problems set forthabove. Certain possible aspects of the present invention are set forthbelow as examples. It should be understood that these aspects arepresented merely to provide the reader with a brief summary of certainforms the invention might take and that these aspects are not intendedto limit the scope of the invention. Indeed, the invention may encompassa variety of aspects that may not be set forth below.

A system is provided for transferring gas into fluids. In oneembodiment, the system is an assembly for delivering oxygen intowastewater. The system includes an oxygenation assembly including apressurizable chamber that receives water from a fluid supply assemblyand oxygen gas from an oxygen gas supply assembly. Advantageously, theoxygen gas supplied pressurizes and maintains the chamber at a pressuregreater than atmospheric pressure (e.g., 300 p.s.i.). The wateradvantageously enters the chamber through an atomizer nozzle that formswater droplets within the chamber. As the water droplets fall within thechamber, oxygen diffuses into the droplets, which collect as a pool ofoxygen-enriched water at the bottom of the chamber. The oxygen-enrichedwater is removed from the chamber and delivered via a hose to atreatment site.

It should be understood that the water to be oxygen-enriched may berelatively clean water from a water supply, such as a tank, pond, lake,stream, or river. Once this relatively clean water is oxygen-enriched,it may be added to the wastewater to raise the oxygen level of thewastewater. Alternatively, the water to be oxygen-enriched may bewastewater skimmed from the treatment tank. The skimmed wastewater isfiltered to prevent the system from clogging, and the filteredwastewater is then oxygen-enriched and returned to the wastewater tankto raise the oxygen level of the wastewater in the tank.

Advantageously, the distal end of the hose includes or is coupled to adelivery nozzle including one or more capillaries through which theoxygen-enriched water effluent passes. The capillaries may bedimensioned to an appropriate length and diameter for a desired flowrate, oxygen concentration, and other flow characteristics such assubstantially laminar and bubble free flow. The capillaries areadvantageously made of silica, and may be dimensioned to a length ofabout 6 cm and an internal diameter of about 150 to 450 microns.Alternatively, the capillaries may be constructed from a variety ofmetals, metal alloys, glasses, plastics/polymers, ceramics or othersuitable materials. For an oxygen-enriched water flow rate of about 1.5gal/min, at about 300 p.s.i., a delivery nozzle including approximately450 such capillaries is particularly advantageous. The capillaries tendto stabilize the gas-enriched water during its delivery into hostliquids at ambient pressure. As a result, nucleation and bubbleformation in the effluent, during ejection from the capillary and mixingwith the host liquid, is minimal or absent despite potentially high gaspartial pressures of the oxygen dissolved in the effluent. An extremelyhigh oxygen transfer efficiency, approaching or even equaling 100percent, is thereby achievable with this approach for oxygenating hostliquids such as wastewater.

Alternately, the oxygen-enriched water is delivered to a treatment sitevia a hose coupled to a plate-based delivery nozzle system. Theplate-based nozzle includes one or more plates having a plurality ofchannels formed therein. The cross-sectional profile of the channels maybe a variety of shapes, e.g., circular, square, rectangular, oval,triangular, etc. Advantageously, the channels in each plate extend alonga portion of the top surface of the plate from a hole in the plate(which advantageously extends between the top and bottom surfaces of theplate) to the plate's edge. The plates are disposed on top of oneanother such that the bottom surface of one plate is mated to the topsurface of an adjacent plate to create fluid pathways between adjacentplates. Further, by placing a bottom plate without a hole beneath astack of plates, and by placing a top plate including a port adapted tocouple to the hose on top of the stack, a plenum is formed within thestack to receive the oxygen-enriched water from the hose and to provideoxygen-enriched water to each of the fluid pathways for delivery to thetreatment site.

Depending upon the circumstances involved in a particular application, anumber of different geometries may be used for the plate-based nozzlesystem. The plates may be of any suitable size or shape, depending uponthe application involved. The channels may extend in each plate to anyof the sides of the plate, so that oxygen-enriched water may bedelivered in any direction. Further, adjacent surfaces of two plates mayhave channels formed therein, so as to create a desired fluid pathwaygeometry when the plate surfaces are brought together, e.g., byalignment of the channels on two separate plates.

An alternate embodiment of the plate-based delivery nozzle system mayemploy one or more conical plates to create an annular array of fluidpathways. The conical plates have a plurality of channels, which extendlinearly along an inner or outer surface between a small and broad endof the conical plates. The conical plates stack in series such that theouter surface of one conical plate is disposed within the inner surfaceof another conical plate, thereby creating an annular array of fluidpathways between adjacent conical plates. The conical plates are thentruncated at one end to provide a common entry position for theoxygen-enriched water and are configured such that the opposite endforms a desired exit surface (i.e., conical, concave, flat, etc.). Theconical plate design may advantageously simplify assembly, as theoxygen-enriched water flow forces the conical plates together duringuse, and may simplify cleaning, as reversed water flow may be used toseparate and clean the conical plates.

By placing one or more delivery nozzles at a treatment site, oxygenlevels at the site advantageously may be maintained or increased bydelivering oxygen-enriched water to the site. For example, in awastewater treatment reactor, oxygen-enriched water may be added to thereactor contents to help support biological degradation activity, reducebiochemical oxygen demand, etc. Advantageously, the water used to supplythe oxygen-enriched fluid supply system is filtered to minimize the riskof the delivery nozzle becoming clogged by particulate matter. The waterused to supply the system may come from any source, e.g., a municipalwater source; a river, lake, or other reservoir; the treated watereffluent of a wastewater treatment operation; the supply of wastewaterto be treated, etc.

Because much of the oxygen provided to a treatment site is in the formof oxygen-enriched water having high levels of dissolved oxygen,oxygenation of the site occurs rapidly as the oxygen-enriched watermixes with the wastewater. Advantageously, delivery of theoxygen-enriched water occurs with minimal bubble formation, sooxygenation efficiencies are achieved which surpass the efficienciesobtainable with commercially available aerators. Thus, the systemprovided advantageously may be used either to replace or to supplementconventional aeration equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects and advantages of the present invention may becomeapparent upon reading the following detailed description and uponreferring to the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating an exemplary embodiment of asystem for oxygenating wastewater including an oxygen-enriched fluidsupply system in accordance with the present invention.

FIG. 2 is a schematic diagram illustrating an exemplary embodiment of anoxygen-enriched fluid supply system in accordance with the presentinvention.

FIG. 3 is a view of an exemplary embodiment of an oxygen-enriched fluidsupply system including an exemplary fluid supply cart and an exemplaryoxygenation cart in accordance with the present invention.

FIG.4 is a cross-sectional view of an exemplary oxygenation assembly inaccordance with the present invention.

FIG. 5 is a cross-sectional view of an alternate exemplary oxygenationassembly in accordance with the present invention.

FIG. 6A is an end view of one embodiment of a gas-enriched fluiddelivery nozzle.

FIG. 6B is a cross-sectional side view of the nozzle of FIG. 6A.

FIG. 7 is an end view of an alternative embodiment of a gas-enrichedfluid delivery nozzle, along with an enlarged view of a portion of thenozzle.

FIGS. 8A-E illustrate another alternative embodiment of a gas-enrichedfluid delivery nozzle, particularly illustrating a plate-based nozzle.

FIGS. 9A-F illustrate exemplary channel geometries that may be used inconjunction with a plate-based nozzle, such as the nozzle shown in FIGS.8A-E.

FIG. 10 illustrates an exemplary clamping assembly that may be used inconjunction with a plate-based nozzle, such as the nozzle shown in FIGS.8A-E.

FIG. 11 illustrates a wastewater treatment plant utilizing a system foroxygenating wastewater including an oxygen-enriched fluid supply systemin accordance with the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The description below illustrates certain specific embodiments or formsthat depict various aspects of the present invention. For the sake ofclarity, not all features of an actual implementation are described inthis specification. It should be appreciated that in connection withdeveloping any actual embodiment of the present invention manyapplication-specific decisions must be made to achieve specific goals,which may vary from one application to another. Further, it should beappreciated that any such development effort might be complex andtime-consuming, but would still be routine for those of ordinary skillin the art having the benefit of this disclosure.

For the sake of clarity and convenience, the various embodiments aredescribed herein in the context of applications generally involvingmunicipal wastewater treatment, including treatment of CSOs, SSOs, andstorm water discharges. However, the present invention may also beuseful in other applications, such as industrial wastewater treatment,e.g., in the petroleum, food, pulp and paper, and steel industries; lakeand stream restoration and/or wastewater treatment; chemical wastewatertreatment; landfill wastewater treatment; ground water treatment;drinking water disinfection with ozone; agricultural or aquaculturalwater treatment; odor control (e.g., on farms); etc. Also, although thepresent system may be used to raise gas levels, such as oxygen forexample, in water or other fluids, for the sake of clarity andconvenience reference is made herein only to wastewater applications.

It should be understood that the gas supplied by the gas supply assemblydescribed below may include oxygen, ozone, carbon monoxide, carbondioxide, hydrogen, nitrogen, air, chorine gas, and/or other treatmentgases, while the gas-enriching assembly described below advantageouslyincludes a gas-absorption assembly capable of raising the dissolved gascontent of the fluid provided by the fluid supply assembly describedbelow. However, again for the sake of clarity and conciseness, the useof oxygen gas will be primarily discussed herein by way of example.

Turning now to the drawings, a wastewater treatment system is providedin which, as shown in FIG. 1, wastewater influent is delivered to areactor 10 for primary treatment. Advantageously, the wastewaterincludes microorganisms for carrying out an aerobic biologicaldegradation process. To support microorganism activity, the wastewateris oxygenated. To provide such oxygenation, a conventional aerationsystem 20, e.g., a mixer or diffuser, and an oxygen-enriched fluidsupply system 30 are illustrated, although it should be understood thatthe fluid supply system 30 may be used alone or in conjunction with theconventional aeration system 20. Advantageously, the system 30 or thesystems 20 and 30 are operated to meet the BOD for the reactor 10. Afteran initial screening and clarification, wastewater from the reactor 10is typically transferred to a secondary clarifier 40 for furthertreatment. A second oxygen-enriched fluid supply system 50 may be used,again either alone or in conjunction with a conventional aeration system(not shown in FIG. 1), to raise or maintain oxygen levels in theclarifier 40 to support microorganism activity. After sufficientprocessing to achieve predetermined levels of suspended solids and BOD,supernatant treated water is removed as an effluent and all or a portionof the settled waste sludge is removed for disposal, with any remainingsludge returned to the reactor 10 to join a new batch of influent fortreatment.

As shown in FIG. 2, one exemplary embodiment of an oxygen-enriched fluidsupply system 30 includes a gas-enriching assembly, such as anoxygenation assembly 60, operatively coupled to both a gas supplyassembly, such as an oxygen gas supply assembly 70, and a fluid supplyassembly 80. The oxygenation assembly 60 advantageously includes anoxygen absorption assembly capable of raising the dissolved oxygencontent of the fluid provided by the supply assembly 80. Theoxygen-enriched fluid exiting the oxygenation assembly 60 advantageouslyis provided to an oxygen-enriched fluid delivery assembly 90 fortransfer to a predetermined treatment site.

Dissolved oxygen levels of the fluid may be described in various ways.For example, dissolved oxygen levels may be described in terms of theconcentration of oxygen that would be achieved in a saturated solutionat a given partial pressure of oxygen (pO₂). Alternatively, dissolvedoxygen levels may be described in terms of milligrams of oxygen perliter of fluid or in terms of parts per million of oxygen in the fluid.

As shown in FIG. 3, one currently assembled embodiment of anoxygen-enriched fluid supply assembly 30 includes a fluid supply cart100 operatively coupled to an oxygenation cart 200. The carts 100 and200 support various respective components of the system 30 anddemonstrate that the system 30 may be small enough to be mobile. Ofcourse, the actual size of the system 30 and the mobility or lackthereof of the system 30 will depend primarily upon the requirements ofa given implementation. For example, if the system 30 were to be used asthe sole means for aerating a reactor 10 in a municipal wastewaterfacility, it would likely be embodied as a fixture at the site. However,if the system 30 were to be used for aerating ponds or as a supplementalaerator in an industrial or municipal wastewater facility, it may beadvantageous to mount the various components of the system 30 on amoveable cart or plat, or even on a trailer or vehicle (not shown).

Water is provided to the fluid supply cart 100 at via line 102 from asource, e.g., the reactor tank 10, a holding tank, a municipal watersupply line, etc., or by a pump withdrawing the water from a tank, pond,stream, or other source. Advantageously, for an application involvingwastewater treatment, the water is input at a rate of between about 5and about 200 gallons per minute, although the input rate may be higheror lower depending upon the application. More specifically, a rate ofabout 60 gallons per minute may prove to be particularly advantageousfor many applications. The provided water advantageously is filtered toremove solid particulate. To provide this function, one or more filters,such as the filters 104 and 106, are coupled to the line 102. It shouldbe understood that multiple filters may be coupled in series or inparallel depending upon the circumstances involved in a particularapplication. As discussed below, a series of filters may be used toremove particulate matter from the incoming water effectively. It mayalso be advantageous to couple filters or sets of filters in parallel sothat one or more filters can be serviced without stopping the treatmentprocess.

In a wastewater treatment application, at least one filter (e.g., a 150to 450 micron filter) may prove to be particularly advantageous,although it should be understood that the type and number of filtersused may depend largely upon the source of the water to be oxygenated.For instance, if relatively clean water from a holding tank is to beoxygenated, a single filter, such as a 150 micron filter, may besufficient to remove particulate matter. However, if wastewater isskimmed off of the reactor 10 and introduced into the system 30,additional filters, such as a coarse filter (e.g., 450 micron) and amedium filter (e.g., 300), may be used to remove large particulatematter before the partially filtered water is introduced to a relativelyfine filter, such as a 150 micron filter. Examples of commerciallyavailable filters include sand filters, cartridge filters and bagfilters, which may be self-flushing or may contain disposable elementssuch as cotton, plastic, metal or fiber filter elements. Also, thefilter size is typically selected to be the same as or smaller than thecapillaries used to deliver the oxygenated fluid.

As shown in FIG. 3, the filtered water advantageously is provided to aholding tank 108, e.g., a 300-gallon tank, via a line 110 that iscoupled to the fluid exit ports of the filters 104 and 106.Advantageously, a valve 111, such as an electronic valve, is operativelycoupled to the line 110 supplying the tank 108 to help control flow intothe tank 108 based upon the level of water in the tank 108. Such controlmight occur, for example, in response to signals generated by one ormore level sensors positioned for controlling the level of water in thetank 108, or by a load cell operatively linked to the tank 108. The tank108 also may include high and low water sensors for safety shut-off.

Fluid exits the tank 108 through a primary line 112 (e.g., by gravityfeed) to a pump 114 run by a motor 116. The pump 114 provides the fluidto the oxygenation cart 200 via a line 118. The fluid may be filteredbefore and after the pump 114 to remove additional particulate matter.As shown in FIG. 3, the line 118 includes a 150 micron filter 202disposed on the oxygenation cart 200. In addition, the pump 114 may beoperatively coupled to an assembly 115, such as an accumulator, fordampening the pulsatility created by the pump 114 so that the fluid isprovided to the oxygenation cart 200 at a steady, continuous rate duringpump operation.

The pump 114 can run continuously or intermittently, and can providevariable or constant flows, depending upon the circumstances involved ina particular application. One example of a particularly advantageouspump is the model #60AG6020 pump available commercially from CAT Pumps,Minneapolis, Minn. To regulate the amount of flow provided to theoxygenation cart 200 for oxygenation, the line 118 via which fluid isprovided to the oxygenation cart 200 may include a modulating valve 119,such as an electronic valve, operable as needed to divert apredetermined portion of the flow via a bypass line 204 back to the tank108. The oxygenation cart feed line 118 advantageously includes a checkvalve 121 to prevent unwanted flow of gas or liquid from the oxygenationcart back toward the pump 114 and tank 108.

The system also may include a flush line 230 between the tank and thedelivery assembly which bypasses the oxygenation assembly. The flushline 230 allows water to pass to prevent dirty water from back flowinginto the system when the oxygenation assembly is in stand-by mode. Asshown in FIG. 3, the flush line 230 advantageously also may provide afluid pathway between the lines 110 and 224.

The oxygenation cart 200 advantageously includes a pressurizable vessel210 that has an interior space 212 in which water from the pump 114 andgas from a gas supply assembly (not shown) are provided. The waterenters the vessel 210 from the feed line 118 via a cantilever-like“stinger” 214 (see FIG. 4) extending from the top of the vessel 210 intothe interior space 212. The stinger 214 advantageously comprises a 1.5inch pipe 215 about 3 feet in length having an inner lumen (not shown)in fluid communication with the feed line 118. The stinger 214 includesone or more nozzles 216 that form fluid ports through which fluid mayexit the stinger's inner lumen and enter the interior space 212. In oneembodiment, each nozzle takes the general form of a pig tail which windsto form a generally conical profile.

The stinger 214 includes one or more nozzle arrays 218 including aplurality of nozzles 216 arranged about the longitudinal axis of thestinger 214. In the disclosed embodiment, each nozzle array 218 includessix nozzles 216 equally circumferentially spaced about the longitudinalaxis of the stinger 214. The stinger 214 may include a plurality ofnozzle arrays 218 spaced along the longitudinal axis of the stinger 214.As shown in the embodiment illustrated in FIG. 4, the stinger 214includes six arrays of six nozzles spaced about six inches apart alongthe stinger 214. Advantageously, the nozzles in the arrays may becircumferentially offset from each other to minimize any overlap in thefluid exit area of each nozzle. This minimizes interference betweenwater droplets from adjacent nozzles and, thus, facilitates theproduction of smaller droplets to optimize gas transfer to the liquid.Alternatively, an umbrella (not shown) may be placed over one or morenozzle arrays to minimize interference between water droplets.

Each nozzle 216 advantageously comprises an atomizer nozzle. Anycommercially available atomizer nozzle may be used depending on thecircumstances involved in a particular application. One particularlyadvantageous nozzle is the Model TF6NN 3/16 stainless steel (0.25 inchnpt) fog nozzle available from BETE Fog Nozzle, Greenfield, Mass. Duringoperation, water exiting the nozzles 216 forms a spray of small dropletswhich contact the oxygen gas in the chamber. Oxygen dissolves in thedroplets, which fall and collect in a pool at the bottom of theoxygenation assembly chamber. The pool advantageously is about two feetdeep in a twelve-inch diameter chamber that is about six feet tall.Furthermore, the number and size of the nozzles are typically selectedto provide a desired throughput. Indeed, should throughput parameterschange, one or more valves (not shown) may be placed in the pipe 215 toselectively activate or deactivate one or more of the nozzle arrays.

The stinger 214 advantageously is removably insertable within theinterior space 212. The stinger 214 may be secured in place foroperation by fastening the inlet end to the top of the oxygenationassembly, e.g., with bolts or other fasteners. Removal may beadvantageous to allow access to the interior of the oxygenation assembly210 and to the stinger 214, e.g., to clean the nozzles, to replacenozzles or other parts, etc.

Oxygen is provided to the oxygenation assembly by a regulated source ofoxygen. Advantageously, the oxygen gas is provided to the oxygenationassembly 210 at about 300 p.s.i. via a line which includes a valveregulating the flow through the line and a check valve that preventsunwanted back flows. The pressure and/or flow through the line mayfluctuate with changes in the water level within the oxygenationassembly 210.

Water is provided to the oxygenation assembly 210 at a pressure greaterthan the pressure in the tank interior space 212—about 300 p.s.i. inthis example. A steady state water supply pressure of about 340 p.s.i.may prove to be particularly advantageous for applications involvingwastewater treatment, although pressure fluctuations commonly occurduring operation of the system. Advantageously, the oxygenation assembly210 includes one or more pressure gauges to allow monitoring and controlof the pressures in the system. The oxygenation assembly 210 and otherparts of the system further advantageously include one or more pressurerelief valves to guard against unwanted pressure build-ups within thesystem.

In this embodiment, fluid exits the oxygenation assembly chamber througha dip tube 222 having an inlet end 224 positioned above the bottom ofthe chamber. By removing fluid from near the bottom of the chamber (asopposed to at the top), gas blow-by is avoided and no bulk gas exits thechamber. The dip tube 222 is connected to an output line 224 having adistal end coupled to a delivery assembly, so as to create a continuousfluid flow path between the pool in the chamber and the deliveryassembly inlet. The output line 224 may include one or more valves,check valves, and/or filters. For example, as shown in FIG. 3, the line224 includes a 150 micron filter 226.

Advantageously, the oxygenation assembly 210 also includes one or morewindows or sight glasses 220 which allow an operator to view theinterior of the oxygenation assembly 210 during operation. Visualmonitoring may be performed, for example, to check the operation of thenozzles (e.g., to monitor fluid droplet sizes, check for pluggingresulting in flow disruption, etc.), to check fluid levels, etc.

In this example, the fluid collecting at the bottom of the chamber has adissolved gas content of about 880 ppm. This dissolved oxygen contentrepresents an increase in oxygen content of about one hundred times ascompared to the fluid entering the chamber before oxygenation. Thedissolved gas concentration, along with the operating efficiency, costs,and flow characteristics of the system, may be widely varied accordingto the operating parameters (e.g., fluid and gas pressures) of thedisclosed embodiments. For example, the apparatus could produce adissolved gas content ranging from approximately 40 ppm to 8000 ppm forsystem pressures ranging between about 14.7 and 3000 p.s.i., dependingon the given operating parameters and system limitations. It should alsobe pointed out, that lowering pressures within the system lowers theamount of dissolved gas content that is achievable, but the lowerpressures also lower the cost of the system. For example, if the systempressures were lowered by about 200 p.s.i. from the 300 p.s.i. range tothe 100 p.s.i. range, the dissolved gas content of the fluid would beabout 275 ppm. In many applications, this oxygen-enriched fluid will bemore than adequate to aerate the wastewater, while providing lowerequipment and operating costs.

As one alternative configuration, the oxygenation assembly 60 mayinclude a plurality of nozzles 250 disposed circumferentially about thewall of a tank 252, as illustrated in FIG. 5. Advantageously, the flowof fluid entering the tank 252, e.g., from a fluid inlet manifold 254,via the nozzles 250 is controlled by a valve 256 adjusted in response tosignals generated by sensors (not shown) for detecting the level ofwater in the tank 252, or by a load cell (not shown) disposed beneaththe tank 252. Oxygen from a regulated pressure source (not shown) entersthe tank 252 at the top, and oxygen-enriched fluid is withdrawn via afluid exit port 258 at or proximate the tank bottom. In an applicationincluding a tank about 5 feet high and 2 feet in diameter (a tank sizeof about 100 gallons), for fluid flow rates of about 15 gallons perminute, a system including four nozzles 250 capable of handling two tofour gallons per minute and generating a droplet cone defined by anincluded angle α of about 90 degrees may prove to be particularlyadvantageous. For higher fluid flow rates, e.g., 60 gallons per minute,a system including eight nozzles for handling six to eight gallons perminute may be advantageous.

One embodiment of the oxygen-enriched fluid delivery assembly 90 mayinclude one or more elongated hoses 301 (FIG. 3) having a proximal endincluding a fluid inlet coupled to the output of the tank of theoxygenation assembly 60 and a distal end including one or more fluidexit nozzles 303. The hose length may vary depending upon thecircumstances involved in a particular application. Advantageously, thefluid exit nozzle 303 comprises a plurality of capillaries, channels, orslits forming continuous fluid pathways that are sized to maintain theoxygen dissolved in the fluid upon exit.

In one embodiment, as shown in FIG. 6A, the fluid exit nozzle 303comprises a collar assembly 300 comprising a main body portion 302adapted with a plurality of fluid exit pathways 308. The portion 302 maybe adapted with a quick couple/disconnect assembly for coupling to thedistal end of the oxygen-enriched fluid delivery hose 301. Alternately,as shown in FIG. 6B, the main body portion 302 may include a femalethreaded portion 304 (advantageously having about 8 threads per inch)for receiving the distal end of the hose 301. An o-ring 306 is used toseal the hose coupling to prevent fluid from the hose from bypassing theexitways 308. Advantageously, the nozzle may be configured to have anouter diameter of about 3 inches; a length of about 2 inches; and up to500 or more fluid exitways, each about 1.5 inches long and 0.005 inchesin diameter. It should be noted that the fluid channels in the fluidexit nozzle 303 advantageously exhibit a cross-sectional area and alength that is chosen to substantially prevent bubble formation and toprovide laminar flow of the gas-enriched fluid upon exit from the nozzle303.

Alternately, as shown in FIG. 7, the fluid exit nozzle 303advantageously comprises a plurality of small capillaries 310, which maybe grouped into tubes 312. For example, each of the capillaries 310 mayhave an inner diameter of about 150 to 450 microns, and may be disposedwith the tubes 312 in groups of about sixty capillaries 310. Each tube312 is formed by extruding silica over the top of the sixty capillaries310 as they are brought together, so as to create a capillary bundlewithin a tube. The tubes 312 advantageously are fixedly attached to eachother (e.g., with an epoxy) at their outer surfaces to create a tubebundle. The tube bundle advantageously is about five inches long andabout an inch in diameter.

To clean the capillary inlets, the distal end of the hose may include avalve (not shown) that can be opened and closed as desired to allowwater to flow rapidly across the capillary inlets to the treatment site.In another embodiment, the capillaries may be flushed by creating aventuri effect that creates backflow in a capillary being cleaned.Alternately, each tube bundle can be replaced and cleaned separately.

In one alternate embodiment illustrated in FIGS. 8A-8E, the fluid exitnozzle 303 may comprise a plate assembly 320 including a stack of plates322. The plates 322 have a plurality of channels 324 along at least aportion of one side between an edge and a hole in the plates 322. Avariety of channel configurations may be suitable, such as thoseillustrated in FIGS. 9A-F. When a plurality of like plates 322 arejoined on top of each other with edges aligned, a block 326 is formedhaving a hole 328 therethrough. A plurality of channels 324 extendthrough the block 326 to the hole 328. When a bottom plate 330 without ahole and a top plate 332 including a port 334 are placed on the block326, a plenum is created.

As illustrated in FIG. 10, the plates 322 may be placed in an assembly350 operable to separate the plates 322 as desired to permit cleaning.The surfaces of the plates 322 exposed to fluid during operationadvantageously are smooth (e.g., as a result of polishing) and arecleaned with alcohol prior to use, so as to minimize the number of sitesat which bubbles may nucleate and grow.

Rather than using flat plates, an alternate embodiment may employ one ormore conical plates to create an annular array of fluid pathways. Theconical plates have small and broad ends, inner and outer surfacesbetween the ends, and a plurality of channels extending between the endson at least one of the surfaces. The channels may extend linearly orcurvilinearly between the small and broad ends, and they may assume avariety of cross-sections and spacings along the surfaces. The conicalplates stack in series such that the outer surface of one conical plateis disposed within the inner surface of another conical plate, therebycreating an annular array of fluid pathways between adjacent conicalplates as the channels are enclosed by the adjacent inner or outersurfaces. The conical plates are then truncated at the small ends toprovide a common entry position for the fluid pathways. Oxygen-enrichedwater enters at the common entry position, flows through the fluidpathways and disperses at the broad ends. The conical plates may bedesigned such that the broad ends form a particular exit surface, forexample, flat, concave, or conical, which may improve flowcharacteristics, provide a specific spray pattern, or alter othercharacteristics. Alternatively, the conical plates may be configuredsuch that the oxygen-enriched water enters at the broad end, truncatedand aligned to form the common entry position, and exits at the smallend.

The conical plate design is advantageous for simplifying assembly, sincethe conical plates are easily aligned, stacked and secured without aseparate mounting apparatus. Properly configured, the oxygen-enrichedwater flow advantageously forces the individual conical plates togetherduring use, thereby maintaining close contact of the surfaces. Theconical plate design is also advantageous for cleaning, which may beachieved by backflushing the conical plate assembly. By reversing theflow through the conical plate assembly, the individual conical platesare forced to separate, and debris is washed away.

The system for oxygenating wastewater including an oxygen-enriched fluidsupply system may be used in a wastewater treatment system, such as amunicipal wastewater treatment plant 400 illustrated in FIG. 11.Specifically, the system may be utilized in one or more of the aerationtanks 402 or clarifier tanks 404. It should be noted that the nozzle(s)303 of the system may be placed in the tanks 402 and/or 404 to provideoxygen-enriched fluid to the wastewater contained therein. In thissituation, it may be desirable to include one or more mixers (not shown)in the tanks 402 and/or 404 in the vicinity of the nozzle(s) 303 tofacilitate oxygenation of the wastewater therein. Alternatively, thenozzle(s) 303 may be placed in a secondary tank 406 located separatefrom the tanks 402 and 404. In this situation, the oxygenated waterflows into the secondary tank 406, which then delivers the oxygenatedwater into the associated tank 402 or 404 via an appropriate deliverysystem, such as a gravity fed line(s) or a pump and line(s) combination.As mentioned above, it may be desirable to include one or more mixers(not shown) in the tanks 402 and/or 404 in the vicinity of the line(s)to facilitate oxygenation of the wastewater therein. By keeping thenozzle(s) 303 out of the wastewater in the tanks 402 and 404, thenozzles will remain much cleaner and, thus, generally operate moreefficiently.

Although numerous embodiments have been disclosed for treatingcontaminated water, many modifications are contemplated to addressspecific wastewater treatment applications requiring gas-enrichment.Wherever aeration of water is required to treat wastewater, thedisclosed embodiments, or modified versions thereof, scaled to produce adesired flow rate of oxygen or air-enriched water, may advantageouslyincrease the oxygen content of the wastewater. Compared withconventional aeration techniques, which use diffusion between theliquid/gas interface (i.e., bubbles), the disclosed embodiments areadvantageously efficient in transferring gas to gas-depleted hostliquids, while providing relatively good control of the level ofdissolved gas in the host liquid. Additionally, the disclosedembodiments may advantageously reduce odors from the wastewater and fromthe gases applied to the wastewater (e.g., by more effective treatmentand/or by reducing the amount of gas escaping, or bubbling out, into theenvironment).

Recognizing these advantages, among many others, various embodiments maybe used for water treatment in agricultural and aquacultural sites. Forexample, animal farms, particularly pig farms, typically generateconsiderable waste in a concentrated area, making waste management, odorcontrol and water contamination a problem. Where crops are grown andcultivated, fertilizers and pesticides may contaminate the water, forexample, by running off the crops and land with rainfall. These waterquality problems are compounded by odor concerns, standard aerationtechniques contribute to the problem. Similarly, marine tanks, fishfarms, and hatcheries typically concentrate marine life in a relativelysmall tank, pool or body of water, wherein water quality and oxygenationmay become a problem. In specialized applications such as these, whereconventional treatment techniques may be insufficient, too costly, orgenerally undesirable, the disclosed embodiments advantageously providea flexible and potentially economical solution to water treatment. Toreduce costs, atmospheric air or compressed air may be used rather thanpure oxygen. For example, it may be more economical to use an aircompressor where the apparatus is used for aerating large bodies ofwater, such as rivers, ponds and lakes. The disclosed embodiments mayalso be designed as, or retrofitted to, a mobile deployment system,which may be moved from one treatment site to another. The mobiledeployment system may be removably or fixably mounted to a truck, to atrailer, to a boat or other watercraft, to an aircraft such as ahelicopter, to carts as disclosed above, or any reasonably mobile unit.A mobile system such as this would be flexible and quite advantageousfor non-site specific and/or emergency applications.

A variety of applications may require alternative gases, other than airor oxygen, to address specific contaminants, purify the water orwastewater, or generally, to attain desired properties of the water orwastewater. For example, anaerobic bacteria are used in some bioreactorsto synthesize organic compounds, with dissolved carbon monoxide as acarbon source. Unlike carbon dioxide, both carbon monoxide and oxygenare only sparingly soluble in water. As a result, conventionaltechniques, such as bubbling or mixing, may fail to provide sufficientcarbon monoxide to keep pace with the metabolic capacity of theanaerobic bacteria. In contrast, a modified system applying thepresently disclosed embodiments could enrich the water or wastewaterwith carbon monoxide at a relatively high transfer efficiency,advantageously approaching 100 percent.

The disclosed embodiments also reduce gas loss, which may be costly andundesirable in many applications. Conventional techniques often involvebubbling a gas through a liquid, providing minimal gas-to-liquidtransfer and considerable gas loss as the gas bubbles exit the liquid.The presently disclosed techniques provide efficient gas-to-liquidtransfer, and do so in isolation from the host liquid, i.e., a hostwater environment such as a pond, reservoir, etc., and drive off VOC'sand odors. Provided that the solubility limit of the gas in the hostwater is not exceeded, bubbles are essentially eliminated, and onlygas-enriched water is delivered to the host water. Furthermore, thetransfer rate is primarily dependent on the flow rate through thedisclosed embodiments, rather than the relatively slow diffusion ratelimiting conventional techniques. The substantial reduction of bubblesand improved gas to liquid transfer is also advantageous to controllingundesirable odors, which are partially caused by the wastewater andpartially due to gas odors (e.g., in conventional techniques, wherealternative gases are bubbled through the wastewater) from incompletegas to liquid transfer.

Accordingly, alternative embodiments may effectively employ gases suchas ozone, carbon monoxide, chlorine gas, inert gas, or other usefulgases. For example, ozone may be used to disinfect or sterilize a liquidsuch as water, by oxidizing contaminants out of the liquid. Contaminantssuch as lead and cyanide, among others, may be effectively ozonated outof a liquid and into an insoluble compound, while any excess from theozonation process generally reduces to ordinary oxygen. Ozone may alsobe used to reduce contamination and waste involved with materialsproduction and processing, such as anodizing aluminum, cross-linking ofsynthetic polymers and natural fibers such as collagen, and bleachingprocesses found in paper production. In the anodizing process, ozonesaturated solvents could be used instead of acids, thereby reducing thetoxicity of waste materials. For further example, hydrogen gas-enrichedwater may be used to enhance the degradation of chlorinated solvents ingroundwater. Alternatively, water enriched with alternative gases, suchas ozone, chorine or gases “toxic” to certain organisms, may be employedin open bodies of water to treat specific problems, such as theeradication of zebra mollusks that clog water vents in the Great Lakes.

Because the embodiments permit delivery of a liquid highly enriched witha gas to be delivered to a host environment without immediate nucleationin the effluent from the nozzles, the gas concentration of the hostenvironment, whether an empty reservoir or a host liquid, can be raisedto hyperbaric levels. Numerous applications that take advantage of thiseffect are now possible, as a result. Several examples follow.

In wastewater treatment, increasing the air or oxygen concentration ofthe host liquid to hyperbaric gas concentrations results inheterogeneous nucleation in the host liquid. The nucleation willtypically take place on suspended particles, including ones ofmicroscopic size. The growth of bubbles on these particles then resultsin flotation of the particles, as they are carried upward by thebuoyancy of the bubbles, to the upper layers or surface of the hostliquid. Skimming the surface of the host liquid can then be used toremove the particulate. This process is more efficient than simplybubbling the host liquid from, for example, an aeration diffuser plateat the bottom of the host liquid. The preformed bubbles will not attachto the small particles with an efficiency comparable to the advantageousefficiency of the heterogeneous nucleation process provided by thepresent embodiments.

Use of the embodiments to increase the oxygen concentration of the hostliquid to hyperbaric levels is advantageous in numerous oxidationprocesses. For example, removal of heavy metals and sulfides in pollutedwater, which can be initiated with addition of a peroxide, can beenhanced by high oxygen concentrations in the water as provided by theembodiments, thereby reducing the need for the peroxide. This is anadvantage, since leftover peroxide is toxic to biologic organisms.

In many bioreactor applications, wherein yeast, fuigi, or bacteriarequire oxygen to produce a desired product or result, the ability toprovide high levels of oxygen in the host liquid would increase theyield of the product or result. A higher concentration of the organismcould be supported in the bioreactor, and when the rate of formation ofthe product is dependent on oxygen concentration, the rate will increasealong with the increased levels of oxygen provided by the embodiments.In this application, the high level of oxygen would be adjusted to bebelow the level that results in excessive nucleation and formation offroth.

In anaerobic bioreactors, carbon monoxide may be used as a carbon sourcefor biosynthesis of organic molecules. Applying the embodiments, highlevels of carbon monoxide, including hyperbaric levels, are achievablein the host liquid, so that the reaction rate of the bioproduct can beaccelerated. An increase in the reaction rate would make the processmore efficient and more economical.

In the beverage industry, a high level of supersaturation of thebeverage with a gas such as carbon dioxide is often desirable. Theembodiments may be used to dispense a beverage highly supersaturatedwith a gas such as carbon dioxide, air, or oxygen. The gas-enrichedliquid may be dispensed either as gas-enriched water that is mixed withordinary syrup, or as the final gas-enriched beverage. Compared to theuse of ordinary dispensers, the gas-enriched beverage provided by theembodiments will be less frothy and will retain the high level of gasfor a longer period of time. Less froth will also expedite filling of abeverage glass or cup.

In the spa industry and in homes, the embodiments may be used to deliverwater with a high level of gas supersaturation as provided in either abath or a shower. The most economical gas is air, but air enriched withoxygen or pure oxygen can be used to provide high levels of oxygen incontact with the skin. High levels of oxygen may be helpful forenhancing collagen synthesis, reducing skin hypoxia, and oxidativekilling of microorganisms. In addition, the fine effervescence thatoccurs in the water in contact with skin provides a unique invigoratingsensation. In addition to air and oxygen, high levels of carbon dioxidein water can also be used for some applications, wherein vasodilation ofskin vessels is desirable. A mixture of gases, such as carbon dioxideand oxygen, may also be beneficial in some instances.

There are numerous other examples, wherein a high level of gas in a hostliquid under ambient pressure is achievable and advantageous with eachembodiment. For example, water enriched with air can enhance water jetcleaning of surfaces and can facilitate snow making at temperaturesabove 0° C., and water enriched with an inert gas such as nitrogen orcarbon dioxide can be used to more efficiently extinguish a fire.

The embodiments may be used with a wide variety of liquids. For example,liquid fuels, such as alcohols, oils, gasoline, and diesel fuel can beenriched with oxygen and, when delivered through a small orifice,subsequent combustion and oxidation of the fuel will be more complete.The presence of oxygen already in the fuel may act as a catalyst and/orthe combustion may proceed at a higher temperature. In addition to thepresence of oxygen in the fuel (the solubility of oxygen in fuels ismuch greater than for water), production of a fine mist from a smallorifice can be used to produce microscopic bubbles suspended in agaseous environment (e.g., air). The microbubbles are produced when theliquid first breaks up into tiny droplets and gas nucleation in eachdroplet produces a microbubble. The thin skin of fuel comprising thewall of the microbubble provides a very broad surface area forfacilitating more complete combustion of the fuel. As a result, fuelefficiency will increase and emission of undesirable reactants,products, and particulate will be reduced.

It should be apparent that the embodiments may also be used to enhanceany chemical or biologic reaction, wherein a high level of gas within aliquid is advantageous at ambient pressure. In addition to ordinaryliquids, liquid melts of solids such as polymers and metals can beenriched with a gas with use of the embodiments.

The present invention may be susceptible to various modifications andalternative forms. Specific embodiments of the present invention areshown by way of example in the drawings and are described herein indetail. It should be understood, however, that the description set forthherein of specific embodiments is not intended to limit the presentinvention to the particular forms disclosed. Rather, all modifications,alternatives, and equivalents falling within the spirit and scope of theinvention as defined by the appended claims are intended to be covered.

1-48. (canceled)
 49. A method of treating a wastewater comprising theacts of: pressurizing a vessel with a treatment gas; and delivering thewastewater, in an atomized state, into the vessel to gas-enrich thewastewater to a desired gas content.
 50. The method of claim 49,comprising the acts of: withdrawing the wastewater from a supply ofwastewater to be treated; and expelling the wastewater, at about thedesired gas content, back into the supply of wastewater.
 51. The methodof claim 49, comprising the act of atomizing the wastewater.
 52. Themethod of claim 49, comprising the act of filtering the wastewater. 53.The method of claim 52, wherein the act of filtering comprises passingthe wastewater through a series of increasingly fine filters.
 54. Themethod of claim 52, wherein the act of filtering comprises passing thewastewater through a 150 to 450 micron filter.
 55. The method of claim52, wherein the act of filtering the wastewater comprises passing thewastewater through a self-cleaning filter.
 56. The method of claim 49,comprising the act of: delivering the wastewater to the vessel through astinger disposed within the vessel, the stinger having a pipe adapted tocarry the wastewater and at least one nozzle, operatively coupled to thepipe, to atomize the wastewater into the vessel.
 57. The method of claim49, comprising the act of: delivering the wastewater to the vesselthrough at least one nozzle disposed adjacent to an inner wall of thevessel, the nozzle atomizing the wastewater into the vessel.
 58. Themethod of claim 49, comprising the acts of: expelling the wastewaterfrom the vessel through a fluid conduit; and passing the wastewaterthrough a nozzle coupled to the fluid conduit.
 59. The method of claim58, wherein the act of expelling the wastewater comprises the act ofpassing the wastewater through a hose.
 60. The method of claim 58,wherein the act of passing the wastewater through the nozzle comprisesthe act of: passing the wastewater through a plurality of fluidpassageways dimensioned to provide a substantially laminar andbubble-free flow.
 61. The method of claim 58, wherein the act of passingthe wastewater through the nozzle comprises the act of: passing thewastewater through a plurality of stacked plates defining a plurality offluid channels therebetween, the fluid channels having an inletfluidically coupled to the fluid conduit and having an outlet.
 62. Theapparatus of claim 58, wherein the act of passing the wastewater throughthe nozzle comprises the act of: passing the wastewater through aplurality of capillaries, each of the capillaries having an inletfluidically coupled to the fluid conduit and having an outlet. 63-75.(canceled)